1. Field of the Invention
The present invention relates to a thin film transistor (TFT) and a method of fabricating the same, and more particularly, to an organic thin film transistor (OTFT) having improved adhesion between source/drain electrodes and a gate insulating layer with no gate leakage current caused by pinhole failure in the gate insulating layer.
2. Description of the Related Art
OTFTs are driving elements expected to be used in next generation display devices. Active research is currently being conducted on OTFTs. OTFTs use a semiconductor layer made of an organic material and have nearly the same structure as silicon TFTs which use a silicon, non-organic semiconductor layer.
OTFTs are generally classified according to the type of the organic material used in the semiconductor layer. The organic material can be a low molecular organic material, such as oligothiophene, pentacene, etc. or a high molecular organic material such as polythiophene-based polymer.
OTFTs may have a top-contact structure or a bottom-contact structure based on whether the organic semiconductor layer is beneath or above the source/drain electrodes. In the top-contact structure, source/drain electrodes are formed on the semiconductor layer. In the bottom-contact structure, source/drain electrodes are formed below the semiconductor layer. OTFTs having the bottom-contact structure are more prevalent since they are less apt to be damaged during subsequent manufacturing processes and can be more easily processed than OTFTs having the top-contact structure.
Even though bottom contact OTFTs are preferred over top-contact OTFTs, bottom-contact OTFTs still have many deficiencies. For example, the adhesion between the source/drain electrodes and the underlying gate insulating layer is weak, the contact resistance between the source/drain electrodes and the gate insulating layer is poor and a gate leakage current occurs through the organic gate insulating layer because of pinhole failure. Therefore, what is needed is an improved design for a bottom-contact OTFT that overcomes the above problems.